Mercury switch



Oct. 18, 1932- c WARNKE 1,883,146

MERCURY SWITCH Filed March 10, 1930 I Patented Oct. 18, 1932 UNITED. STATES PATENT orrrcs CARL J. WABNKE, OF ELKHART, INDIANA, ASSIGNOB BY MESNE ASSIGNMENTS, TO MINNEAPOLIS-HONEYWELL REGULATOR COMPANY, OF MINNEAPOLIS, MINNESOTA,

A COBPORATIQN OF DELAWARE MERCURY SWITCH v Application filed March '10, 1980. Serial No. 434,497.

My invention relates to mercury switches.-

The life and capacity of the various types of mercury switches may be greatly enhanced by incorporating in the switch the invention of Patent 1,598,874, granted September 7, 1926, to L. A. M. Phelan. In general, the invention of this patent comprises an hermetically sealed container or casing, iron electrodes, a body of mercury cooperable with said electrodes, and an atmosphere of hydrogen within the case or container. But even with a mercury switch so constituted it has been found that after the switch has been flashed or operated a certain number of times, the switch will fail due to the mercury separating and leaving a portion stringing or hanging between and short-circuiting the electrodes in the open position of the switch. I have discovered that the primary cause of this failure is due to the absorption by the mercury of impurities contained in the so-called commercially pure hydrogen and also present to some extent on the surfaces of and in the electrodes. The impurities of i the electrodes are in the form of oxide coathas been purified as far as known means permit. I have determined that the impurities resent in the so-called commercially pure ydrogen gas consists of small amounts or traces of nitrogen, oxygen, moisture or water, hydrocarbons, due to absorption of small amounts of oil from the apparatus and possiblv other substances. 7

One of the principal objects of my invention is to prolong the life of a mercury switch of this character so that the switch will operate with efiiciency a great many times more than mercury, switches now known or used. In general, this object is attained by reducing to a minimum the oxide, scale or other impurities on the surface of the electrodes and by employing substantially pure and extremely dry hydrogen which has been previously processed in a novel manner to impart to it certain novel properties or characteristics whereby it is effective to protect the mercury against contamination over a relatively long period of time.

To determine the probable life of a mercury switch of any type and structure it is customary to subject a number of the switches produced by the same manufacturing process and of the same materials to the so-called flash test. The switches to be tested are selected at random so that they represent on the whole the average type of switch being manufactured. The flash test consists in incorporating such a mercury switch in an electrical circuit wherein it will be subjected to a known load and a known voltage and in op erating the switch at a given speed until it fails. In this way the number of times that the switch may be flashed or operated is accurately determined and this affords a reliable indication of the probable life of average switches of the same type and structure. When mercury switches containing an atmosphere of the so-called pure hydrogen available prior to my invention were subjected to the flash test, the life of such switches varied between one thousand and two thousand flashes, whereas with the same type and structure of switch containing an atmosphere of the substantially pure and dry hydrogen produced by my process the life of the switches were prolonged to between twenty-five hundred and four thousand flashes.

I believe that these advantages result largely from the employment in the switchof an atmosphere of substantially pure and extremely dry hydrogen. Such hydrogen carries no impurities or moisture to be absorbed by and contaminate the mercury. On the contrary, the hydrogen gas produced by the present invention will have the capacity of absorbing some of the impurities that may walls of the evacuated vessel, and preclude the absorption of such minute traces of such by the mercury over a long period impurities of time;

The apparatus for and process of purifying and drying the hydrogen does not per se form the subject matter of this application.

In general, however, my process consists in first passing commercially pure hydrogen through coils which are air so as to condense as far as possible all of the free moisture in the hydrogen and as many of the other impurities as will be removed from the gas by such extremely low temperatures as that to which the coils are subjected- After leaving the coils the hydrogen is stored in holders or tanks from which it is passed, when it is to be used, through one or more and usually a series of arcs formed in a series of hermetically sealed and connected chambers and subjected to the high temperature of the arc and also to the action of the vaporized and ionized constituent of the arc, which constituent is of such character or has such properties-as to be capable of absorbing or removing all remaining moisture in the gas and of converting the remaining impurities into solids which are precipitated from the gas in the form of fine powders. Usually the arc is formed between an electrode such as molybdenum or tungsten and an electrode of sodium, potassium, or other metal of the sodium group. The sodium, potassium, or the like, is selected because it is hygroscopic, and also because when vaporized and ionized it has the property of combining in the heat and environment of the arc with impurities in the hydrogen gas. It is believed to be important to so constitute the electrodes of the are that the vaporized and ionized constituent of the arc will be hygroscopic for the reason that if the moisture or water is allowed to remain in the hydrogen it will, when in the mercury switch, act as a catalyst and accelerate those reactions that tend to contaminate the mercury. Further, the high temperature and environment of the arc or arcs induces a combination between the hydrogen and oxygen to form water which is immediately absorbed by the vaporized sodium. In other words, the arc influences impurities to' combine with each other and with the hydrogen and to form either powdery solids which are precipitated, or water which is absorbed by' the sodium.

After passing through the arcs the gas is then drawn oil" through a long tube which is filled with cotton or other filtering medium acting merely to prevent the powdery solids from being entrained with the purified gas and carried into the switches. The tube is connected to the suction manifold of a pump surrounded by liquidpresence of any sodium. It has,

of the; ype widely used for filling mercury switches with an inert, are suppressin gas.

It is thought'that the gas producer? as a result of my process and utilized in my improved mercury switch is highly purified and extremely dry hydrogen as the spectrum. of-

contains-only hydrogen-lines. Furthe-gas 'tber, all of the various chemical tests indicate the. gastoconsist-only of hydrogen. For example, the highly purified and dry gas produced by my method has been passed through phenophthalein without any indication of the however, some peculiar chemical'and physical properties. When passed through carbon-tetrachloride a reaction ensues which results in the generation of hydrochloric acid and the reduction of carbon. This is rather remarkable and unexpected as the so-called purehydrogen heretofore-available will produce no reaction when passed through carbon-tetrachloride. Another unexpected efiect produced is that when a mercury tube (mercury to mercury makeand break type) containing my dry, pure hydrogen is agitated in the dark before it has been flashed, the dry, pure hydrogen fluoresces or gives oil a blue glow.

With ordinary hydrogen there will be no glow or fluorescense until after the mercury switch (mercury to mercury type) containing the same has been flashed a few times and further, after continual flashing with a switch having the ordinary commercial hydrogen, the fluorescense entirely disappears.

The invention is adapted for embodiment in any of the various types of structures of mercury switches. A number of representative forms or types of switches are shown in the accompanying drawing, in which Figure 1 is a view in longitudinal vertical. section of one type of switch in which my invention may be embodied;

Figure 2 is a similar view showing another type of switch which my invention may be used to advantage;

Figure 3 shows one form of a switch in which my inventionv ployed;

Figure 4 is a similar view showing still another type of switch to which my invention is applicable; and

Figure 5 is a view in cross section on line 5-5 of Figure 4. I

Referring to the drawing, and more particularly to Figure 1, the numeral 1 designates an outer casing or envelope of glass through the wall of which lead-in wires'2 and 3 are sealed, the lead-in wires carrying electrodes 4 and 5 at their inner ends. Within the switch a body of mercury 6 is provided and in the closed position of the switch bridges the electrodes 4 and 5 whereas in the open position of the switch the mercury. flows away from the electrodes to break the circuit in which the sleeve type may be emswitch is incorporated. During the manufacduced air and filled with an atmosphere of substan-.

tially ure and extremely dry hydrogen proy my process. The switch shown in Figure 2 has an outer glass envelope as designated at 10. At oneend the envelope is provided with a pinch seal 11 about lead-in wires 12 and 13 welded as at 14 and 15 to iron electrodes 16 and 17 with which a body of mercury 18 is cooperable. The atmosphere in the switch shown in Figure 2 is also my substantially pure and dry hydrogen.

In the form of the switch shown in F igure 3 an outer soft glass envelope 20 is provided.

2 An inner sleeve 21 or are resistant material such as quartz, hard glass, porcelain, or the like, is provided within the outer envelope and is supported at one end on a ring 22 consisting of cement impregnated asbestos which acts to support the inner sleeve and also to form a partition in the outer envelope. A body of mercury designated at 23 is provided within the outer envelope and is adapted when the switch is moved to open position to separate or divide into two portions, one contained within the inner sleeve and on one side of the partition 22 and the other contained on the opposite side of the partition 22 and in the space between the inner sleeve and the outer envelope. The parts of the switch are so proportioned that these portions of the mercury unite and divide on a surface of the are resistant sleeve.

Electrodes 24 and 25 are provided and 4 extend into the inner sleeve and into the space between the inner sleeve and the outer envelope, these electrodes being welded to leadin wires 27 and 28 sealed through the wall' of the outer envelope. This is the Well known sleeve type of switch but its action and operation may be greatly improved by utilizing in the switch an atmosphere of my substantially pure and extremely dry hydrogen and preparing the electrodes thereof in the manner roposed by this invention and to be hereina ter more fully described.

The type of switch shown in Figures 4 and 5 represents a recent development of the sleeve type switch shown in Figure 3 and as illustrated includes an outer casing or envelope 30 which may be of soft glass or other suitable material and which has one end flattened and sealed about lead-in wires 32 and 33, the inner end of which wires are welded as at 34 and 35 to electrodes 36 and 37. An inner protective element in the form of a cup or thimble 38 is provided and may be constituted of any suitable are resistant material such as ceramic, hard glass, quartz, porcelain, or the like. The protective element 38 has one end closed as at 39 and has its other end open as at 40. The open end of the protective element has integrally formed therewith angularly extending legs 41 which project from its lower portion and some extent of occluded gases.

with an upper lug 42, the legs 41 and lug 42 being loosely fitted in and having supporting engagement with the inner wall of the outer envelope. The closed end 39 of the protective element 38 is provided with an aperture 43 through which the electrode 36 passes, the electrode 36 having its inner end of angular form and extending down to the lower portion of the protective element. A coating of cement designated at 44 is applied to the electrode 36 and to its weld 34 for securing the electrode 36 to the protective element 38 and to provide an insulating covering which prevents short-circuiting of the electrodes.

A body of mercury 45 is provided in the outer envelope and when the envelope is appropria-tcly tipped or tilted, this body of mercury divides into two portions, one of which is trapped in a thimble 38 and the other of which is contained in the space of the outer envelope and on the outside of the thimble. The parts are so proportioned that the mercury unites and divides on a surface of the protective element. The cfiiciency of this type of mercury switch and its life is greatly enhanced by employing in. the switch an atmosphere of substantially pure and extremely dry hydrogen produced by my process and by preparing the electrodes and protecting them during the manufacturing process.

It is to be understood that I do not claim to be the inventor of any of the specific constructions or types of switches herein shown and described. These structures have been illustrated as typical of the various types of switches and as indicating the adaptability of my invention to be embodied in any of the various types or structures of switches. In

.any of these types of switches my invention resides in the utilization of electrodes, preferably constituted of iron or of a metal of the iron group, that have been relieved as far as practicable of all oxide or scale and to In conjunction with electrodes so constituted I employ an atmosphere of substantially pure and extremely dry hydrogen which has been purified and dried by passing it through an hermetically sealed chamber and subjecting it in such chamber to the action of an electric are having as its vaporized constituent sodium or its equivalent. Hydrogen of this quality or character employed as the atmosphere in the switch will not'contaminate the mercury and not only this but the hydrogen so constituted has the capacity of absorbing and holding over a long period of time such impurities as remain on or in the electrodes. The net result of this action is that the life of the switch is prolonged two or three times that of the best types of mercury switches heretofore known or used. The electrodes after being welded to the leadingin wires are carefully cleaned, that is to say,

.small amounts of impurities on contaminating the long period of time.

-ties, a body of all oxide or scale on the surfaces thereof are removed. This cleaning operation occurs subsequent to subjecting the electrodes to electrical or electro-chemical treatment which tend to relieve them of occluded gases. During the welding operation the electrodes are protected from the action'of the heat by clamping them in jaws, pliers, or the like, which are shaped to completely cover and protect the surfaces of the electrodes. When the leading-in wires are being sealed 1n the outer casing of the envelope the electrodes are located within the envelope and are thus protected from the flame. In some instances the electrodes, after being sealed in the envelope, may be subjected to an electro-chemical cleaning operation but this is not essential. All that is necessary with my atmosphere of substantially pure and dry hydrogen is that the electrodes be free of any material amount of scale or coating on the surfaces thereof as the hydrogen I employ has the capacity of absorbing and holding or in the electrodes and protecting the mercury from contamination thereby over a long period.

I claim:

1. A mercury switch comprising an hermetically sealed container, electrodes therein, the surfaces of the electrodes being substantially free of any material amount of oxide, scale, and impurities, a body of mercury in the container cooperable with the electrodes, and an atmosphere of substantially pure and extremely dry hydrogen filling the container and having the property of absorbing and holding the impurities of the electrodes and precluding such impurities from contaminating the mercury over a long period of time.

mercury switch comprising an hermetically sealed container, electrodes therein, said electrodes having their surfaces substantially free of oxide, scale, and impurities, a body of mercury in said container c0- operable with said electrodes and an atmosphere of hydrogen in "said container, said hydrogen being so substantially pure and so extremely dry as to have the'capacity to react withcarbon-tctrachloride whereby in the switch the hydro-gen has the property of absorbing and holding the impurities of the electrodes to prevent such impurities frommercury over a relatively I 3. A mercury switch comprising an hermetically sealed container, electrodes therein, said electrodes having their surfaces substantially free of oxide, scale, and impurimercury in said container cooperable with said electrodes and an atmosphere of hydrogen in said container, said hydrogen being so substantially pure and so extremely dry as to give 01f a blue glow or uorescense when within the mercury switch phere'of hydrogen that has been previously electrodes, an atmospurified and dried by passing it through an hermetically sealed chamber and it in said chamber to the action tric are having as its vaporized a metal of the sodium lent thereof.

' 5. A mercury switch comprising an hermetically sealed container, electrodes therein having their surfaces substantially free of any material amount of oxide, scale and impurities, a body of mercury in the container cooperable with the electrodes, and an inert arc suppressing atmosphere filling the container and having the property of absorbing and holding impurities of the electrodes and precluding such impurities from contaminating the mercury over a relatively long period of time.

In witness whereof, I hereto afiix my signature.

CARL J. WARNKE.

subjecting of an elecconstituent group or the equiva- 

